This is out of the NHRA rule book changes in May

An SFI 27.1 ribbon-type or mesh-type window net is mandatory on any full-bodied car running 7.49 (*4.49) or quicker. For full-bodied cars running 7.50 (*4.50) to 9.99 (*6.39) or if vehicle runs 135 mph or faster a ribbon-type or SFI 27.1 mesh-type window net is mandatory unless otherwise specified by class requirements. SFI 27.1 window net, when required, must be updated at two-year intervals from the date of manufacture.